Gas fuel feed device



Patented June 11,' 1935 GAS FUEL FEED DEVICE Delos W. Davisson, Ferdinand G. Welke; and

Almy C. Maynard, San Francisco, Calif., assigners to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application February 16, 1932, Serial No. 593,304

2 Claims.

This invention relates to a fuel feed device for internal combustion engines and is more specifically concerned with the operation of such engines upon a gaseous fuel.

It is the usual practice to operate internal combustion engines either upon a liquid or gaseous fuel. Both types of fuel are used in stationary engines, but until recently it was not generally practical to utilize gaseous fuel for traction purposes, owing to the difficulty of maintaining a supply of such fuel. However, it is now feasible to use gas fuel owing to the availability of cylinders of compressed hydrocarbon gases commonly known as bottled gas.

This bottled gas comprises light petroleum fractions such as propane, butane and iso-butane which are gaseous at normal temperatures and pressures. The advantages of using bottled gas instead of gasoline for the operation of trucks and motor stages are increased when used in conjunction with the refrigerating or cooling system disclosed in U. S. Patent No. 1,905,971, issued April 25, 1933.

Stationary engines are often run on natural gas or manufactured gas, but owing to the nature of their work acceleration periods and quick changes in operating speeds are not required of them. Consequently, a very simple type of fuel metering device is only necessary. On the other hand, in the operation of automobiles and trucks changing road a'nd traffic conditions necessitate a flexible operation. In the modern liquid fuel carburettor these needs are provided for by the amount of throttle opening as well as by the use of dash pots, accelerating wells, multiple jets et cetera.

In our co-pending patent application Serial No. 582,574, we have disclosed a form of fuel feed device which gives a exible performance with gaseous fuel. Under certain conditions of throttle opening and load, we have encountered slight periods of reduced power or so-called at spots with this device. It is our belief that these fiat spots are caused by air passing to the motor by way of the gas feed lines which in effect form a by-pass around the throttle valve.

A purpose of this invention is to eliminate the periods of reduced power or flat spots. Another purpose of this invention is to devise a simple gas fuel feed apparatus such as can be utilized when the gas feed is effected solely by the vacuum existing in the intake manifold of 'the motor.

Briefly our invention comprises, in a device for introducing fuel gas above and below a throttle valve situated in the intake manifold of a motor, means for preventing air being carried from below the throttle valve to above the throttle valve except by opening said throttle valve.

The principle of operation and the features of our invention will be more fully understood from the following detailed description throughout which reference is made to the accompanying drawing. y

Fig. I is a View in elevation showing the device attached to a gasoline carburettor, only the main outline of which is shown.

Fig. II is a vertical sectional view along line A-A of Figure I.

Fig. III is a horizontal sectional view along line B-B of Fig. I.

Fig. IV is a vertical sectional view along line B-B of Fig. I.

Referring to Fig. I, numeral (I) represents the barrel of an ordinary carburettor having an air intake valve (2), a butterfly throttle valve (3), a Venturi tube (4) and a gasoline jet (5). The flange (6) of the carburettor is connected to a complementary flange ('I) of the intake manifold (8) only part of which is shown.

The body (9) of the gaseous fuel adapter isattached to the carburettor and the inlet manifold by means of a metal gasket (IIJ) clamped between the flanges (E) and (l). The body (9) of the gaseous fuel adapter is shown in more detail in Figures II, III and IV.

To the middle portion of the body (9) is connected a gas supply line (I I). This gasV line terminates in a main passage way I2). A branch (I3) of the main passage Way leads by Way of valve (I4) and pipe (I5) into the carburettor above the throttle valve (3). The main passage way (l2) is connected to a pipe (I6) discharging into the carburettor below the throttle valve (3) preferably through the wall of the Venturi tube (Il).

A flapper check valve (I'I) is placed in the main passageway so that gas can only flow to one direction in pipe (I6), namely, towards the carburettor.

The extent to which this flapper valve can open is controlled by a screw (I8) and lock nut (I9). The rotatable valve (I4) in the branch passageway (I3) is connected by means of an arm (20) and rod (2|) to the arm (22) of the throttle valve (3).

The method of operatic-n is as follows: i

When the motor (not shown) is turned over and the throttle'valve slightly opened, the vacuum produced in the manifold causes gas to be drawn 'from line (I I). This gas ows through valve (I4) and pipe (I5) to the motor.

Little or no gas will pass to the motor by pipe (I6) as with the throttle valve only slightly open the vacuum above the throttle valve will generally be greater than below the throttle valve.

As the throttle is opened, valve (I4) also opens, admitting more gas to the motor. When more power is desired of the motor and thethrottle valve opened beyond a certain point. the velocity of air through the Venturi tube (4) will cause amounts of gas to flow by way of apper -valve (I1) and pipe (I6) to the motor.

Without the apper valve (I1) under certain conditions of operation, for instance when the vacuum above the throttle valve is lnigh, the throttle valve (3) and the valve (I4) being only partially open, there would be a tendency for air to be drawn from the air intake through pipe (I6) and to become mixed with the fuel gas being drawn into the Carburettor by pipe (I3).

If air'thus became mixed with gas the strength of the gas-air mixture would be toolean causing back-firing and flat spots4 in the operation of the motor'.

By the use of flapper valve (II) the ow of air through pipe (I6) is prevented as any movement through pipe (I6) will cause the valve to close flrmly.

The idling speed of the motor can be regulated by suitable adjustment of the linkage between valves (3) and (I4) as will be readily understood from Fig. I.

By means of screw (23) in line (I5) and screw (I8) in line (I6) the strength of the gas-air mixture can be suitably regulated.

It will be understood that when a gas source under pressure is used that a suitable pressure reducer such as are in common use must'be connected in gas feed line (I I). ducer should preferably be adjusted so that a slight vacuum inline (II) will cause the gas to flow.

When the gas supply is being used the gasoline supply to the carburetor is of course turned off.

Our device in no wise interferes with the existing gasoline carburetor; it is possible to run the Imotor on gasoline or other liquid fuel by simply shutting 01T the gas supply and turning on the liquid fuel supply to the carburetor.

We claim as our invention:

1. A gas fuel feed device for an internal combustion motor comprising: an intake pipe adapted to be attached to said motor, a throttle valve in said intake pipe, a gas valve attached to said intake pipe, a gas supply line connected to said gas valve, a conduit leading from the gas valve into the intake pipe below said throttle valve, a conduit leading from said gas supply line into the intake pipe above said throttle valve, and a one way apper valve in the rst mentioned conduit whereby air is prevented from passing to the motor by way of said conduits.

2. A gas fuel feed device as in claim 1 but differentiating therefrom by having controlling means for controlling the degree to which said flapper valve maybe opened.

ALMY C. MAYNARD. FERDINAND Gr. WELKE. DELOS W. DAVISSON.

This pressure re- 

